/*

 * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package sun.security.util;

import java.io.IOException;

import java.security.*;

import java.security.spec.*;

import sun.security.util.ObjectIdentifier;

import sun.security.x509.AlgorithmId;

import sun.security.rsa.RSAUtil;

/**

 * Utility class for Signature related operations. Currently used by various

 * internal PKI classes such as sun.security.x509.X509CertImpl,

 * sun.security.pkcs.SignerInfo, for setting signature parameters.

 *

 * @since   11

 */

public class SignatureUtil {

    // Utility method of creating an AlgorithmParameters object with

    // the specified algorithm name and encoding

    private static AlgorithmParameters createAlgorithmParameters(String algName,

            byte[] paramBytes) throws ProviderException {

        try {

            AlgorithmParameters result =

                AlgorithmParameters.getInstance(algName);

            result.init(paramBytes);

            return result;

        } catch (NoSuchAlgorithmException | IOException e) {

            throw new ProviderException(e);

        }

    }

    private static AlgorithmParameterSpec getParamSpec(String sigName,

            AlgorithmParameters params)

            throws InvalidAlgorithmParameterException, ProviderException {

        if (params == null) return null;

        if (sigName.toUpperCase().indexOf("RSA") == -1) {

            throw new ProviderException

                 ("Unrecognized algorithm for signature parameters " +

                  sigName);

        }

        // AlgorithmParameters.getAlgorithm() may returns oid if it's

        // created during DER decoding. Convert to use the standard name

        // before passing it to RSAUtil

        String alg = params.getAlgorithm();

        if (alg.equalsIgnoreCase(sigName) || alg.indexOf(".") != -1) {

            try {

                params = createAlgorithmParameters(sigName,

                    params.getEncoded());

            } catch (IOException e) {

                throw new ProviderException(e);

            }

        }

        return RSAUtil.getParamSpec(params);

    }

    // Special method for setting the specified parameter bytes into the

    // specified Signature object as signature parameters.

    public static void specialSetParameter(Signature sig, byte[] paramBytes)

            throws InvalidAlgorithmParameterException, ProviderException {

        AlgorithmParameters params = null;

        if (paramBytes != null) {

            String sigName = sig.getAlgorithm();

            params = createAlgorithmParameters(sigName, paramBytes);

        }

        specialSetParameter(sig, params);

    }

    // Special method for setting the specified AlgorithmParameter object

    // into the specified Signature object as signature parameters.

    public static void specialSetParameter(Signature sig,

            AlgorithmParameters params)

            throws InvalidAlgorithmParameterException, ProviderException {

        String sigName = sig.getAlgorithm();

        if (params != null) {

            sig.setParameter(getParamSpec(sigName, params));

        } else {

            try { 

                sig.setParameter(null);

            } catch (UnsupportedOperationException e) {

                // ignore for maintaining backward compatibility

            }

        }

    }

}